Feature detection and extraction was developed for image processing to identify objects (features) within an image. This may be useful as a part of computer vision, image search, object recognition, and other such image-analysis systems. The act of feature detection involves identifying points or areas of potential interest in an image (e.g. edges, corners, etc.), often using gradient analysis. The act of feature extraction involves generating a multi-dimensional vector representation of a small patch of the image containing the feature of interest. The resulting output of feature extraction is a feature descriptor.
Feature descriptors are then used, for example, in object recognition or image matching processes. For instance, the set of feature descriptors from an image may be stored in a query database containing sets of feature descriptors for a large number of images. This can enable such functions such as facial recognition, for example.
The concept of feature detection and extraction may also be extended to video, which may be considered a series of pictures. The Motion Picture Experts Group (MPEG) intends to standardize the descriptors for video as Compact Descriptors for Video Analysis (CDVA). MPEG is exploring tools for video processing and analysis with the goal of reducing “the data amount for the resulting video descriptors transmission or storage” and achieving “interoperability of implementations, applications and databases”. Note that in MPEG CDVA, descriptors for a video sequence are extracted in a picture by picture (or frame by frame) manner, and then compressed.
The large number of feature descriptors that may be extracted from each picture of a video leads to a large data burden in identifying and storing and transmitting feature descriptors, even when compressed. It would be advantageous to provide for a system and method of feature descriptor extraction that maintains or improves the discriminative power (i.e. accuracy) of the feature descriptors while reducing or maintaining the number and complexity of the descriptors.
Similar reference numerals may have been used in different figures to denote similar components.